Carburetor



April 24, 1934-l A R. voN BECKER r-:l'l AL l 1,956,367

` CARBURETOR Filed April 4.v 1932 Fate-interi ipr. 24, 1934 iliiii@ STT CARBURETR Reinhold von Becker, Darmstadt, Germany, and ,l'esdimir Dordievitch, Paris, France Application April Ll, 1932, Serial No. 603,183 En Germany April 9, 1931 s claim. (oi. ,afer-'win Our invention relates to improvements in spray carburetors for internal combustion engines, in which the fuel supply increases with the quantity of air Flowing through the carburetor and depend- 5r ing upon the speed of the engine. The invention can be applied to all carburetors which are provided with an arrangement for maintaining oonstant the fuel level, for example a float chamber, and which have an idle running nozzle terminating on the edge of the closed throttle valve into the induction conduit, the discharge aperture of this nozzle being controlled by the throttle valve. The invention consists in a novel construction of this idle running nozzle, which enables a quantity of fuel to be supplied also throng the idle running nozzle said quantity of fuel increasing in the same proportion as the quantity of air iiowing through the carburetor.

An embodiment of the invention is illustrated by way of example on the accompanying drawing in which:-

Fig. 1 shows the carburetor in elevation, partly in longitudinal section.

Fig. 2 is a part section on a larger scale along line II-II in Fig. 1, the thickness of the throttle with respect to the size of the opening 17 being also shown;

Fig. 3 is a diagrammatic view showing the theoretical cross sectional shape of the idle running nozzle necessary for the throttle closing position illustrated, together with the practical form of construction shown in dotted lines, in a section along line Ill-111 in Fig. 1. Also in this figure the thickness of the throttle is shown as in Fig. 2.

As shown in Fig. 1, the carburetor consists Aof a mixing tube l leading to the engine and provided with air induction socket 2 and oat chamber 3. The iioat chamber 3 can be closed by a cover 4 and accommodates a iloat 5 which ad- 40v .iu-sts in well known manner the float needle 7 controlling the fuel admission 6 and thus maintains constant the fuel level in the float chamber 3. The float chamber 3 communicates by a channel S with a cavity l0 in the bottom of the mixing tube 1 closable by a plug 9, the main injection nozzle l1 projecting from said cavity. The mixing tube is narrowed by a venturi l2 at the height of the mouth of the nozzle 11 which is situated above the level of the liquid in the float chamber so that the air flowing past attains its maximum s eed at this point and draws fuel from the nozzle l1.

Between the mixing tube 1 and the float chamber 3 there is inserted in a bore 13 a nozzle tube 55 14 connecting the channel 8 with an additional nozzle bore 15, which terminates in the mixing tube l at the height of the throttle valve 16 and is closed by the throttle valve when the latter is closed.

Such carburetors are known as regards their Si@ construction and operation and do not constitute the subject matter of this invention.

The usual employment of idle running nozzle bores with a circular or slot-shaped passage is open to the objection that, when the throttle valve, 16, is uniformly oscillated, the nozzle aperture is not freed so that it uniformly increases. Moreover since the mixing tube 1, due to the turning movement of the throttle valve 16, is opened by differently large cross sectional areas according to the position of the throttle valve with the same angular adjustment, the quantity of air flowing through does not increase uniformly with the opening of the throttle valve, and therefore,

a different mixture results for the different po- 7x5 sitions of the throttle valve during the idle running period, that is when the throttle valve still more or less covers the mouth of the idle running nozzle.

In order to attain a uniform mixture of air qu and fuel in all these positions, the mouth of the idle running nozzle has, according to this invention, a cross section, the width of which in vertical direction changes in a proportion constant within practical limits to the passage cross sec- 35 tions of the induction tube actually freed by the throttle valve.

It is well-known that the area of the mixing tube opened by the throttle valve varies substantially as the cosine of the angle made by the throttle with the axis of the mixing tube. Therefore, in order to bring the cross-section of the mixing tube actually opened by the throttle in a proportion constant within practical limits to the opened passage cross section of the slow running nozzle, it is necessary that the width of the passage 1'? of the slow running nozzle in vertical direction, i. e. in the direction of the axis of the mixing tube, change or increase according to the change in the cosine of the angle made by the 1.00 throttle with the axis of the mixing tube.

The theoretical cross sectional form for a certain mixture proportion of air and fuel, resulting for the closing position shown in Fig. 1, is illustrated in full lines a, a in Fig. 3.

As this cross sectional form can be only carried out with difculty owing to the curved shape of the two side edges 3:, in the practical oonstruction the cross section is made of a form approximating the theoretical shape, for example 1:19

. on a larger scale.

that of a triangle 17, shown in dotted lines in Fig. 3.

Fig. 2 shows a cross section through the auxiliary nozzle tube 14 corresponding to Fig. 1 and The triangular shape of the additional nozzle mouth 17 is clearly shown in this ligure.

By 'constructing the auxiliary nozzle in this form, one can, when the engine is running idle, maintain the air-fuel mixture supplied to the cylinders in a mixture proportion constant Within practical limits.

We claim:-

1. In a spray carburetor for internal combustion engines, in combination with a mixing tube, an air intake tube, a throttle valve in said mixing tube and a main nozzle projecting therein, an idle ruiming nozzle terminating laterally into said mixing tube having its mouth at the height 0f said throttle Valve and adapted to be closed by said throttle valve in the closed position of said valve, the horizontal Width of the mouth of said idle running nozzle liberated by the throttle varying in the direction of the axis of said mixing tube in a proportion constant Within practical limits to the cross-sectional area of said mixing tube actually liberated by said throttle Valve.

2. The combination as specified in claim 1, in Which the discharge aperture of said idle running nozzle has a cross-sectional area approximately covering the theoretical shape.

3. The combination as specified in claim 1, in which the discharge aperture of said idle running nozzle is of triangular cross-sectional area approximately covering the theoretical shape.

REINHOLD von BECKER. J E SDIMIR DJ ORDJ EVITCH. 

